The first reason is, that you've put the patch to mediafire (shoud be dropbox, if I understand the rules of the site).
The second reason is, that you didn't include any screenshots. And even those can be false sometimes (some people were actually trolling with fake screenshots, made with picture editors and were not really doing any hacking).
So it doesn't matter if it is a demo, screenshots are mandatory and in the exact format too (a png picture of the exact resolution of the emu output).
It would also be wise to name the console (NES in this case) and the CRC of the original file to patch to. Again doesn't matter if it is a demo, the patching process is the same, as if it would not be a demo.